A pressure sensor for detecting small pressure differences and low pressures

A capacitive pressure sensor of substantially ceramic material comprises a thick base plate (100), a front plate (140) having the same thickness as the base plate and a movable diaphragm (120) located between the front plate and the base plate. Capacitor electrodes (121b, 121a) are provided at the surface of the diaphragm facing the base plate and form a measurement capacitor. The diaphragm (120) is extremely thin and is produced by sintering a ceramic material such aluminium oxide. Owing to a pressing process used during the sintering a strong, very thin diaphragm is obtained having no mechanical stresses and fracture indications. It can be produced to have a very small thickness in order to provide pressure sensors having a high sensitivity, which can also for high-vacuum applications tolerate to be subjected to the atmospheric pressure. A shielding plate (110) can be inserted between the base plate (100) and the diaphragm (120) in order to provide both electrical shielding and to form a reference capacitor having a reference pressure for compensating the measurement capacitor. The shielding plate (110) can also be extremely thin, having a thickness down to a thickness corresponding to the thickness of the diaphragm (120).